Picture transmission



Dec. 16, 1930.

'r-f. scHR-rER 1,784,850

PICTURE TRANSMIS S ION Filed Feb. 23. 1929 HIXXH lull" vwem'oz FRITZscHRoTER Patented Dec. 16, 1930 ATENTEOFFICE FRITZ sonneries, or"BERLIN, YVGERMANVY,

ssienon froV GESELLSCHAFT non DRAHTLOSE TELEGRAPHIE TMI. B. H., QFBERLIN, GERMANY' ricrunniinnnsiviission Application led February 23,1925 ,.Seria1 No. 342,059, and in Germany March 3, 1928.

The present invention relates to Vpicture transmission and isparticularly directed to: radio transmission of pictures, althouglnofycourse, it is possible tor use the scheme for wire line or wired radio'systems.

The obiect of the present invention isv to produce a method andapparatus for trans-y mitting pictures in which the detrimental, effectsof the fadingV phenomena ,during operation are substantially eliminated,and this result has been accomplished, in the present instance, bycontinually altering the transmitted wave. n .i

According tothe present invention, the transmitted Wave is changed astoits frequency in the short time intervalbetween the exploration andscanning of any two successive lines onia picture which is` to betransmitted. `It is, of course, possible, and also within the spirit andscope ofthe invention, to make this shift in frequency even during thetransmission of any ture without waiting until the completion of anyparticular line of scanning, should conditions where this is necessaryarise. However, only inconnection with the former of the two abovedisclosed methods, sincea system will readily suggest itself to anyoneskilled in the art to which the invention .relates by Which the modifiedform of frequency shift may be accomplished.v f 1 Other objects lof the`invention willof course, at once become apparent from a reading of thefollowing specification and claims when considered together with theaccompanying drawing in which a` single figure thereof illustrates oneform which my invention may assume although, it is to be understood,that certain modifications and changesv may be made thereto providedthey fall within the spirit'and scope of the hereinafter ap pendedclaims. f

The means, as shown bythe drawing, for

accomplishing the objects of the invention may consist, for instance, intheuse of a revolving contact which is coupled with the scanning deviceor associated with the 'pic-Y ture carrying drumand whose positionsactuy ate the element Vwhereby the frequency of the one line of thepic-` the invention will .be described transmitted wave is altered inthe ,time interval betweenthe exploration of any two successive picturelines. VOfjcciurse, it is possible to change the frequency in many ways,for example, by causing the Contact to change the connection and flow ofadirect current,l or, perhaps, break the iiow of a direct current whichserves to magnetize an iron core choke .coil with the result that theinductance theremission by melting use `of two distinctV fre-A quencies.y v f In'` so far as the use of the hereinafter described method, andthe arrangement to be adopted at tlie'receiving end, are concerned,automatic changes in the receiving apparatus must `be effected broadlyin accordance with changes in the transmission wave length. F orinstance, inthe case Vof heterodyne reception the locally generated`,wave should suitably be so changed that the same beat frequency willalways be preserved. However, it is also possible to work without anyalterations of the heterodyne frequency by adjusting the heterodyne to afrequency which is equal to the frequency ofthe longer wave minus halfthe difference between the two transmission waves or the frequency oflthe shorterwave plus half thedifference bef tween the two transmittedwaves. In this case the same differential note willbe ob.

tained by both transmission waves while the heterodyne remains unvaried.

If the transmission takes place on two waves which are widely separatedfrom each other then, under certain conditions, it mayparatusrunchanged, butV whether lornotl thehas `loeenfaboven pointedoutT however, theAV changes 1n the.-transmitted` wave. length. are

small it is possible to leave the receiving apreceiving apparatus ischanged or unchanged will depend. largely-upon workingrenditions,=

which, aredifferent for each case.

Now referring more particularly to" the 0 this description, ash'owin of"one A'@Xenifpiication of 'they idea embo'dyinfrthis invention; itliaslbeenl-pr'el drawing accompanyin su'pposed'that 1the carrier'frequencyin rela-- tion to the receiverfislittleL changedlsothatA thespecial jmeasures described for cliang-ingj the 'receiverjinayi bedispensed withflinthis-f As shown 1by the accompanying drawn-1g,-l

they picture drum 1 carries the pictureftoloe` transmitted and for the*purpose of? concrete illustration oflone embodiment 1offthe inven byfany cci tionA al reflection type lof transmitter using; opaque.orfsemiopaque pictures has"- beenv shown. vThis picture carrying drumis driven*- from -af synchronous motorJ of3v any desired typeorch'aracteristics, whiclr is maintained with aV like element atthetransmitter.

motor has not been illustrated.Y

As shown bylthe drawing, the angle a desig` nates the portionv ofthepicture drum Awhich is free from the picture elements. ttis thisportion of the picture drum which servesffor securingthe picture to tliedrumrand uby* the present invention thisisztlrep'ortion ofthe" picturecarrying drumY whose Vpassage'time before :the scanning 4element r`is tobe util-ized* iny order to vary the wave length ofthe transmitter.

The photo 'cell 2,' which isA preferably,v of the annular type for aAreflection typetransmitter, is arranged adjacent the picturercarv ryingdrum 1for the purpose ofscanning the picture.v Lightfroma source 3 isprojectedthrough a. small diaphragm-Ml and' lens fi' to' produce a"point image of the luminous source 3; upon the 'surface oftlfefpicturedrum. Forthe purpose of*producing` the picture ,current 'carrier wavefor" amplifica tion a f perforated-flight' chopper disli' 5 has been.providedl Infaccordance with' tHe p`res` ent illustration. separate.motor 6"' has been shown for the purpose ovfdrivin'g :this ,pereforatedglightchopper.disliz Associated; withatheg picturedrum.M leise.

commutatinggarrangement 7 whichpthrough an appropriate speed reductionor driving l turnedlthatvtlie.contact '.9lpasses over the con- 7:

V,well .known scheme inz synchronism For'v convenience of illustrationthis synchronous gear mechanism, is so arranged as to run at onehalf thespeed of the Vpicture carrying drum 1. The commutator 7 has half of itscircumference covered by a conducting segment 8, while the remainingpart of the commutatorlis an insulating.segmentj Aicircuit L throughAthe battery 11'l can' Ib eA ma deL through theelectromagnet 10 by wayof the sliding Contact 9V only, whenthe commutator isssok i ductingsegment S'b'utlwhil'e contact 9 rests L ontlieinsulating portion of thecommutator there is an open circuit in this path".

The change from Athe current'winterruption period (as shown by thedrawing) to the currentfl'ow period by Wiayi of Ithe-fContact. 9 takes#place aty the instantiwhen the-1 ang-le a i passes throughth'escanning@zonel infffront *of* tlieipheto cell52 Tliisfaetion'fisutil-ized:fori v the purposef of 'influencingiftheil transmitteri asfollows: l/Vh'enI currentflowsfrornthebatteryV 11' through theelectromagneti 10;?` the contactQgthe conducting segment ISan'dba-ckftol ground, avrelayor; switch 112- is 'closed' and -2 in vthis -mannerja portion-of a-resistance-13 connected 1in series with adfirect :currentgen:- erator115 is shortf circuit-edf Tlliisfres'ufltsin. a change inthe anode potential -upon a-vacLfv` uum tube 16` acting-across the'terminals.- of resistori 141. A s

The: tube-'1th"isi-so` arrangedias 4to fact? ash-'a 2 crystalcontrol-led generator. The tube ar-v rangement* 16^comprisesl anoscillatory cir cuit consisting j of parallellyl connected` in.'-ducta-nce 173 and `fca-pacity 18 K and .in additionv avticllerlor#regeneration coil 19' anda control or masterlcrystalQOy madefrom quartz;

It has beenfound,f to besure, that the-Wave length of the oscillationcircuit`- is1 kept? ati a constant Vvalue inside relatively narrow' jbounds by the aid 'of ltlfeicrystal-QO 'butthat inside th'e'saidinterval it is liablefto loe-acted upon'loy` variations `of the anodeApotential on the oscillator '16 with aresult that''accordingv to whetherthe relayor switch =12isclcsed orl 3G open' asomewhat changed control`frequency will be produced. This frequencyfwillbe altered from one lineof the 'picture carried by' the drum 1`to theneXtiinfaccordancewith thearrangement hereinbefore `disclosedl' m5 As shownby the drawingthev'energy fromV the' oscilla'L-torl 16 isamplified 'by means ofl anamplifier '21 land4v is then di'rectedto ainodula-y tor 22 which' isalso suppliedy with current variations jfrom" thei photo cell Qi wliicliarerst amplified yin; an amplifier 1 2'4"; offwel-l knowncharacteristics ortype: The Ioutpnofi` Vthe modulator 22 isthendirecte-dto ati-ans;

les m quency Will'be insuredautomatically.' Fr l instance, the scanningdisk note could be varied, if such a disk is used at the sending end ofthe system.

Having now described my invention, what I claim is l. In a picturetransmission system, means for scanning and analyzing'l a picture fortransmission, means for modulating a transmitted Wave in accordance Withthe point for point intensities of light and shade on the transmittedpicture, and means for continually changing the frequency of thetransmitted carrier at the period between any tivo successive line forline scannings of said picture.

2. ln a picture transmission system, a rotatable picture support-ingelement, means for .scanning a picture to be transmitted, means forproducing a plurality of individual carrier frequencies, means formodulating said carrier frequencies in accordance With the varying peintfor point tone intensities on the said picture, and means operable fromsaid picture supporting element for alternately changing from one to theother of said carrier frequencies at predetermined time intervals duringthe scanning of a plurality of lines of said picture.

3. in a picture transmission system, means for scanning a picture to betransmitted, means for producing a plurality of individual carrierfrequencies, means for modulating said carrier frequencies inaccor-dance With frequencies for transmission, means connected With saidoscillator for changing the frequency thereof., a rotatable picturesupporting and scanning means for analyzing a picture for transmission,relay means operable from said picture carrying element at apredetermined point in the rotation thereof forV controlling saidfrequency varying means for varying the generated frequencies, and meansfor modulating each of the controlled genera-ted frequencies of saidoscillator in accordance With the intensity of light and shadow onelemental areas of said picture surface.

FRITZ SCHRTER.

the varying point for point tone intensities Y on the said picture, andmeans for alternately changing from one to the other of said carrierfrequencies at the end of each successive line for line scanning of saidpicture.

4. In a picture transmission system, a picture supporting element, meansfor illuminat ing elemental areas of the picture carried by saidsupporting element, means for producing a relative movement between saidilluminating means and the said supporting element for successivelyscanning the picture along a plurality of adjacent paths, means forgenerating a carrier frequency for transmitting the picture, means formodulating' said carrier frequency in accordance With the intensity oflight and shadow on elemental areas of the said picture, and meansoperable at predetermined points in the scanning of the` supportedpicture deter-minable by pre-established points in the relative movementbetween the picture support and illuminating means for varying thecarrier frequency Within predetermined limits.

5. In a picture transmitting system, a rotatable picture supportingelement,means for scanning a picture carried by said supporting element,a generator for generating carrier frequencies for transmission, aresistor element in said generator circuit, means operable from saidpicture supporting element for varying the value of the resistance insaid generator circuit at the yend of each line of

